In the field of hydrocarbon recovery, there are many situations in which it would be desirable to determine the presence of certain fluids at a location or several locations in the downhole environment. For example, in cementing operations, it may be desirable to determine when water is present in order to maintain the integrity of the cement layer. In steam flooding operations or other stimulation operations, it would be desirable to determine the presence of a treatment fluid. In production operations, it would be desirable to determine the presence of hydrocarbon, water, or acid in the well. Once the presence of these fluids is known, remedial or other downhole operations may be conducted accordingly.